move buffer caching on to the buffer

actionpack/lib/action_controller/metal/data_streaming.rb

@@ -85,6 +85,10 @@ def initialize(path)
           @to_path = path
         end
 
+        def body
+          File.binread(to_path)
+        end
+
         # Stream the file's contents if Rack::Sendfile isn't present.
         def each
           File.open(to_path, 'rb') do |file|

actionpack/lib/action_controller/test_case.rb

@@ -136,10 +136,6 @@ class TestResponse < ActionDispatch::TestResponse
   end
 
   class LiveTestResponse < Live::Response
-    def body
-      @body ||= super
-    end
-
     # Was the response successful?
     alias_method :success?, :successful?
 

actionpack/lib/action_dispatch/http/response.rb

@@ -80,11 +80,21 @@ def initialize(response, buf)
         @response = response
         @buf      = buf
         @closed   = false
+        @str_body = nil
+      end
+
+      def body
+        @str_body ||= begin
+                        buf = ''
+                        each { |chunk| buf << chunk }
+                        buf
+                      end
       end
 
       def write(string)
         raise IOError, "closed stream" if closed?
 
+        @str_body = nil
         @response.commit!
         @buf.push string
       end
@@ -222,9 +232,7 @@ def message
     # Returns the content of the response as a string. This contains the contents
     # of any calls to <tt>render</tt>.
     def body
-      strings = []
-      each { |part| strings << part.to_s }
-      strings.join
+      @stream.body
     end
 
     EMPTY = " "